Line Level Converters... any measurements?

[mga2009]

Hi,

I would like to know if "line level converters" (that is the kind of device that converts your amplified output to an unamplified one so it can be fed to an external AMP or to the ADC of a DSP, typically used in car audio) affects negatively to audio quality.

What kind of perfromance you should get? Are they any measurements regarding this?

Can this be an easy way to get a 2vRMS+ output from an old receiver, so it can be fed to a better quality external amp?

Looking forward to your thoughts.

 

[LTig]

I don't understand what you're looking for. You can connect any amplified output to an amp or DAC. You just need to match the levels using volume and/or gain controls.

Edit: Do you look for something to convert speaker output level to line level? This can be done using a simple voltage divider with 2 resistors. Done right it has no negative effect on SQ.

 

[mga2009]

I don't understand what you're looking for. You can connect any amplified output to an amp or DAC. You just need to match the levels using volume and/or gain controls.

Edit: Do you look for something to convert speaker output level to line level? This can be done using a simple voltage divider with 2 resistors. Done right it has no negative effect on SQ.

Yes, I am looking to convert speaker output level to line level.

There is no negative effect on SQ? How is it done properly?

 

[DVDdoug]

It's normally just a voltage divider (2 resistors for each channel). The signal quality shouldn't be degraded at all.

The sound quality may not be better through another amp... The noise and distortion from the 1st amp will be attenuated proportionally with the signal and then everything will be re-amplified. But, distortion, and frequency response MIGHT be better with the higher impedance load. Then every amplification circuit "in the chain" adds SOME noise & distortion so theoretically it could be worse.

Can this be an easy way to get a 2vRMS+ output from an old receiver,

We don't know how much voltage is coming-out of the old receiver so we really don't know how much attenuation we need. You can calculate/estimate the maximum from the power rating but that's the maximum and it will be lower and unknown with "typical" input signals and the volume control around mid-range, etc.

 

[Gringoaudio1]

Hi,

I would like to know if "line level converters" (that is the kind of device that converts your amplified output to an unamplified one so it can be fed to an external AMP or to the ADC of a DSP, typically used in car audio) affects negatively to audio quality.

What kind of perfromance you should get? Are they any measurements regarding this?

Can this be an easy way to get a 2vRMS+ output from an old receiver, so it can be fed to a better quality external amp?

Looking forward to your thoughts.

Why would you do this? If you take the output of the old receiver at the speaker terminals you will just be reproducing all the flaws of the receiver including its power stage. A ‘better’ amplifier won’t help sound quality. If it is more power you need then that is another matter. A more powerful amp won’t sound ‘better’ though. If you had super inefficient speakers you might need more power I suppose. But this is a real ghetto hack.

 

[antcollinet]

Why would you do this? If you take the output of the old receiver at the speaker terminals you will just be reproducing all the flaws of the receiver including its power stage. A ‘better’ amplifier won’t help sound quality. If it is more power you need then that is another matter. A more powerful amp won’t sound ‘better’ though. If you had super inefficient speakers you might need more power I suppose. But this is a real ghetto hack.

Also - just take the whatever input is going into your reciever, and put it into the final amp. Thus avoiding all the distortions of the power stage of the receiver.

 

[mga2009]

Why would you do this? If you take the output of the old receiver at the speaker terminals you will just be reproducing all the flaws of the receiver including its power stage. A ‘better’ amplifier won’t help sound quality. If it is more power you need then that is another matter. A more powerful amp won’t sound ‘better’ though. If you had super inefficient speakers you might need more power I suppose. But this is a real ghetto hack.

I understand that apart from power, I would also coult get better distortion numbers if the external amp is better than the integrated.

Anyways, I may also use this to feed the ADC on a DSP as my old receiver does not have any EQ capabilities.

 

[mga2009]

Also - just take the whatever input is going into your reciever, and put it into the final amp. Thus avoiding all the distortions of the power stage of the receiver.

Not possible really. This is an old Onkyo 313 and I am using HDMI input.

-. The distortion on the power stage of the receiver "should" be low as I am not using it at full power?

 

[LTig]

Not possible really. This is an old Onkyo 313 and I am using HDMI input.

This one? https://av-receivers.net/onkyo/onkyo-tx-sr313-review/
You could use the VCR/DVR output but its level is fixed so you must control the volume at the power amp (if it has a volume control).

-. The distortion on the power stage of the receiver "should" be low as I am not using it at full power?

Distortion will be somewhat lower when you have no speaker connected.

 

[LTig]

Yes, I am looking to convert speaker output level to line level.

There is no negative effect on SQ? How is it done properly?

Just two resistors per channel, see here. R2 should not be higher than around 500 Ohm, and it should be connected close to the power amp input (with a short cable).

 

[antcollinet]

Not possible really. This is an old Onkyo 313 and I am using HDMI input.

-. The distortion on the power stage of the receiver "should" be low as I am not using it at full power?

Even so - you cannot get better sound since you will be cascading the distortion AND noise from two amplifiers.

Plus a lot of the non linearity will be voltage related - so if you have the receiver at higher volume (which you will need to do to keep noise down) you'll still get a lot of its distortion.

Effectively it seems you just want to use the receiver as a DAC. If so the suggestion to use the DVR output is the way to go. If you need volume control put a passive volume pot in the way.

 

[Speedskater]

Radio Shack had an automotive unit:
12-1338 Line-out Converter
for connecting amps or EQ's to car radios that didn't have line level jacks.

 

[mga2009]

This one? https://av-receivers.net/onkyo/onkyo-tx-sr313-review/
You could use the VCR/DVR output but its level is fixed so you must control the volume at the power amp (if it has a volume control).

Distortion will be somewhat lower when you have no speaker connected.

The receiver does not have any output, apart from the speaker outputs... all others are inputs.

Even so - you cannot get better sound since you will be cascading the distortion AND noise from two amplifiers.

Plus a lot of the non linearity will be voltage related - so if you have the receiver at higher volume (which you will need to do to keep noise down) you'll still get a lot of its distortion.

Effectively it seems you just want to use the receiver as a DAC. If so the suggestion to use the DVR output is the way to go. If you need volume control put a passive volume pot in the way.

OK, but if there will be cascading noise and distortion... how much is it? At least I would like to know how much does a line level converter affects SQ, noise and distortion (in essence, this is my question)

Radio Shack had an automotive unit:
12-1338 Line-out Converter
for connecting amps or EQ's to car radios that didn't have line level jacks.

Yes! There are many designs and models. This is commonly usedin car audio

 

[LTig]

At least I would like to know how much does a line level converter affects SQ, noise and distortion (in essence, this is my question)

It doesn't, as was told before.

 

[mga2009]

It doesn't, as was told before.

But some post says it will ADD noise and distortion...

 

[LTig]

But some post says it will ADD noise and distortion...

Nope, not the voltage divider itsself.

 

[Gringoaudio1]

Nope, not the voltage divider itself.

The voltage divider is a simple two resistor per channel passive device.
Just get a more modern receiver with more connections and low power instead of a new separate power amp perhaps?
Why amplify the sins of your existing receiver with another amplifier with its own flaws?

 

[antcollinet]

But some post says it will ADD noise and distortion...

No, it will simply take the noise and distortion added by the reciever, and pass it on (signal and noise distortion - reduced to line level) to the amplifier. Which will amplify it again, and add its own noise and distortion.

 

[mga2009]

OK. Thanks to all for the clarification...

Now... whats the best cheap line level converter I can get? and... how can I measure the output sensitivity I am getting from my AVR+line level converter?

 

[pseudoid]

I am kinda confused about what (and how) you are trying to accomplish but I have 2 simple questions for you:
Q#1) Have you tried just taking the speaker outputs and connecting them to whatever/where-ever you want to feed it to (but at lower signal levels?)?
Of course, making sure to turn the Volume way down before doing so?
Q#2) Does this Onkyo have a (front panel?) headphone jack? Which, usually, is a (resistive) tap from the power amp outputs (going to the speaker connectors)?